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From: Jan Beulich <jbeulich@suse.com>
To: Hongyan Xia <hx242@xen.org>
Cc: jgrall@amazon.com, "Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
	xen-devel@lists.xenproject.org
Subject: Re: [PATCH v9 10/13] x86/smpboot: switch clone_mapping() to new APIs
Date: Tue, 20 Apr 2021 14:32:49 +0200	[thread overview]
Message-ID: <de0df262-6c83-41d2-02d6-ce56d484baa2@suse.com> (raw)
In-Reply-To: <d55bcecc33df5b277bc3e1dbb48826bc816d8d10.1617706782.git.hongyxia@amazon.com>

On 06.04.2021 13:05, Hongyan Xia wrote:
> @@ -742,51 +742,58 @@ static int clone_mapping(const void *ptr, root_pgentry_t *rpt)
>          }
>      }
>  
> +    UNMAP_DOMAIN_PAGE(pl1e);
> +    UNMAP_DOMAIN_PAGE(pl2e);
> +    UNMAP_DOMAIN_PAGE(pl3e);

Just one minor remark: A pedantic(?) compiler might warn about the
setting to NULL of pl3e here, when

>      if ( !(root_get_flags(rpt[root_table_offset(linear)]) & _PAGE_PRESENT) )
>      {
> -        pl3e = alloc_xen_pagetable();
> +        mfn_t l3mfn;
> +
> +        pl3e = alloc_map_clear_xen_pt(&l3mfn);
>          rc = -ENOMEM;
>          if ( !pl3e )
>              goto out;
> -        clear_page(pl3e);
>          l4e_write(&rpt[root_table_offset(linear)],
> -                  l4e_from_paddr(__pa(pl3e), __PAGE_HYPERVISOR));
> +                  l4e_from_mfn(l3mfn, __PAGE_HYPERVISOR));
>      }
>      else
> -        pl3e = l4e_to_l3e(rpt[root_table_offset(linear)]);
> +        pl3e = map_l3t_from_l4e(rpt[root_table_offset(linear)]);

... it is guaranteed to get initialized again before any further
consumption. IOW strictly speaking the last of those three would
want to be unmap_domain_page(), just like you have ...

> @@ -802,6 +809,9 @@ static int clone_mapping(const void *ptr, root_pgentry_t *rpt)
>  
>      rc = 0;
>   out:
> +    unmap_domain_page(pl1e);
> +    unmap_domain_page(pl2e);
> +    unmap_domain_page(pl3e);
>      return rc;
>  }

... here.

Jan


  reply	other threads:[~2021-04-20 12:33 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-06 11:05 [PATCH v9 00/13] switch to domheap for Xen page tables Hongyan Xia
2021-04-06 11:05 ` [PATCH v9 01/13] x86/mm: rewrite virt_to_xen_l*e Hongyan Xia
2021-04-20 12:17   ` Jan Beulich
2021-04-21 11:33     ` Hongyan Xia
2021-04-21 11:39       ` Jan Beulich
2021-04-06 11:05 ` [PATCH v9 02/13] x86/mm: switch to new APIs in map_pages_to_xen Hongyan Xia
2021-04-06 11:05 ` [PATCH v9 03/13] x86/mm: switch to new APIs in modify_xen_mappings Hongyan Xia
2021-04-06 11:05 ` [PATCH v9 04/13] x86_64/mm: introduce pl2e in paging_init Hongyan Xia
2021-04-06 11:05 ` [PATCH v9 05/13] x86_64/mm: switch to new APIs " Hongyan Xia
2021-04-06 11:05 ` [PATCH v9 06/13] x86_64/mm: switch to new APIs in setup_m2p_table Hongyan Xia
2021-04-06 11:05 ` [PATCH v9 07/13] efi: use new page table APIs in copy_mapping Hongyan Xia
2021-04-06 11:05 ` [PATCH v9 08/13] efi: switch to new APIs in EFI code Hongyan Xia
2021-04-06 11:05 ` [PATCH v9 09/13] x86/smpboot: add exit path for clone_mapping() Hongyan Xia
2021-04-20 12:29   ` Jan Beulich
2021-04-06 11:05 ` [PATCH v9 10/13] x86/smpboot: switch clone_mapping() to new APIs Hongyan Xia
2021-04-20 12:32   ` Jan Beulich [this message]
2021-04-21 13:39     ` Hongyan Xia
2021-04-06 11:05 ` [PATCH v9 11/13] x86/mm: drop old page table APIs Hongyan Xia
2021-04-06 11:06 ` [PATCH v9 12/13] x86: switch to use domheap page for page tables Hongyan Xia
2021-04-06 11:06 ` [PATCH v9 13/13] x86/mm: drop _new suffix for page table APIs Hongyan Xia

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